linear positioning sensing

[SK500]

Hello,

I am doing some product sourcing work for a company. I need to find a solution to an engineering task relating to linear positioning sensing.
I have circular track with a 100 foot circumference on a horizontal plane. There are motorized carts that travel around it, each cart’s movement is independent of one another. I am looking for a system that can report the position of each cart at any moment in time, while in motion or at rest. (Absolute position, not incremental)

This is an example of a possible choice:

http://www.pepperl-fuchs.com/select..._currentTreeName_select=tree_classification_1

Also, I would like the sensor technology to be able to withstand different weather conditions.


Please let me know if you have any suggestions or know of any companies that are in this field.

Many Thanks.

 

[MacGyverS2000]

I don't know about COTS solutions, but how about marking the track itself and having the cart read the location? What degree of positional accuracy do you require? For about $2 a simple circuit could read a simplified barcode applied to the track every foot or so. For durability, instead of printing the barcode, make it by removing slivers from a metal plate and use a reflective IR sensor.

Dan - Owner

http://www.Hi-TecDesigns.com

 

[hallb]

SK500,

On the oval track, do you need just an angular location of each cart, or do you need the exact position (such as angle and radius from an arbitrary point). If you only need angular position, I agree with macgyvers2000. This information, as well as an approximate budget are important pieces of a prospective solution.

 

[SK500]

macgyvers200,
I think you mean an encoding rail along the track, yes you are right, thats what I want to do.
Accuracy that I require is 1" - 1/4" ! , but let's just say 1/4" to be conservative.

Do you know of a company who does that IF sensors.

 

[SK500]

SK 500,
The track is completely circular. Just need the angular position (just along the circumference), the radius will be the same since it's a circle.
Approxiamate budget...cost is not an issue, as along as the system is sophisticated.

 

[MacGyverS2000]

Again, I don't know of any COTS solutions, so may be someone else can point one out. However, even 1/4" resolution is easily doable... orient the barcode vertically to save on horizontal space.

For 100 linear feet marked at 1/4" resolution, you'll need 13 bits for encoding (assuming no CRCs or redundancy). Easiest solution would be a vertical array of 13 IR sensors on each cart. The marked track would contain a vertical array of 13 holes, punched to mark a 1, non-punched to mark a 0. If you want sophistication and a small barcode, you could use fiber optics to keep the array size tiny, but then you run into alignment issues.


Dan - Owner

http://www.Hi-TecDesigns.com

 

[BobM3]

If dirt or moisture might be a problem, anything optical could have problems. You might want to consider something magnetic.

 

[SensorGooRoo]

A magnetic solution is a good way to do this one - I have worked with a company that set up a great linear position system using a special tape they constructed and a very fine resolution linear magnetic sensor. you could add a wireless - zibsbee option for wireless or connect to the agv itself.

you could try

http://www.inproxsensors.com

and ask for special magnetic projects.